As pure air is one of the essentials of good health, it follows that one of the chief duties of a housekeeper is to see that the family supply of this necessary element is properly regulated. Very few housekeepers realize the importance of ventilation in promoting the general health and comfort of the family. As the scope of this book prevents anything further than a few suggestions or a brief outline of the principles underlying these important questions, we will adopt the rule followed in the preceding chapter, beginning with the cellar: 1. See that surface water is carried away from all sides, by either natural or artificial drains, and that the cellar is perfectly dry. Have enough windows in the cellar to secure plenty of light and air, and see that they are opened every day. 2. Have the cellar thoroughly cleaned and whitewashed with lime at least once a year, twice if possible, in the spring and fall. 3. Keep the coal in a dry place. 4. Do not allow decomposed vegetables, or old bottles, which may cause unpleasant odors, to accumulate in the cellar. Unless there is a special cellar for vegetables, where they may be kept at a proper temperature and carefully looked after, it is much better for the housekeeper to purchase in small quantities. Remember the ventilation of the cellar is of the greatest importance, and should never be neglected. One of the most noted authorities in America, on the question of ventilation, says: "The three important objects are, (1) To provide an abundance of pure air in every part of the house; (2) To avoid drafts, either hot or cold; (3) To provide means of escape for foul air and odors." As before stated, much of the vigor, comfort and happiness of the family depends upon attention to these matters. Next to the cellar, we will take the living and sleeping rooms, which should be thoroughly aired every day, not simply by opening the window a few inches at the bottom, or--as in some double or outside windows--by a little opening a few inches wide; but by causing a circulation of air in the room, and providing an outlet for foul air near the ceiling, which may be done by lowering the window from the top. An outlet for foul air is quite as important as an inlet for fresh air. If there is a skylight at the top of the house, it should be kept open a few inches all the time as an outlet for impure air; an attic window will serve the same purpose. Have doors and windows so arranged that a draft may be made possible when needed to change the air of a room quickly, or in airing bedclothes; two windows being of course more desirable. After dressing in the morning, open the window of the sleeping room, top and bottom; turn back the clothes over one or two chairs; place pillows and mattress where they will have a current of fresh air; also open the closet door. Do not allow water to remain in a bedroom more than twenty-four hours.